Silane-Containing Self-Adhesive Resin Cement vs. Conventional Strategies in Fiber Post Application: A Push-Out Bond Strength and Failure Mode Study

This study evaluated the push-out bond strength (PBS) and failure modes of fiber posts cemented with silane-containing self-adhesive resin cement (SARC) compared with conventional SARC and universal adhesive strategies, considering the effects of root section and aging. Ninety single-rooted human premolars were equally assigned to three cementation protocols: silane-containing SARC (PANAVIA SA Cement Universal), conventional SARC (RelyX Universal), and universal adhesive plus SARC (Scotchbond Universal Plus + RelyX Universal). Each group was divided into two aging subgroups: 24 h water storage and thermal cycling (10,000 cycles between 5 °C and 55 °C, 30 s dwell time; n = 15). After root canal treatment and post space preparation, glass fiber posts were cemented, and each root was sectioned to obtain six slices. PBS was measured using a push-out test, and failure modes were examined under stereomicroscopy. Data were analyzed using three-way ANOVA, post hoc tests, Spearman’s correlation, and logistic regression (α = 0.05). Cement type, root section, and aging significantly influenced PBS (p < 0.001). PBS decreased from coronal to apical sections, and thermal cycling reduced PBS in all groups. The universal adhesive plus SARC achieved the highest PBS, while conventional SARC had the lowest PBS. Cementdentin adhesive failures (FM2) predominated overall, with proportions varying between 43% and 90%, and higher PBS values were associated with fewer FM2 failures. The combination of a universal adhesive with SARC provided superior bonding compared to simplified protocols. Although silane-containing SARC improved bonding relative to conventional SARC, durable adhesion to radicular dentin remains challenging, particularly in apical regions.